Apparatus and method for removing wood defects



June 23, R v APPARATUS AND METHOD FOR REMOVING WOOD DEFECTS Filed July22. 1968 m I! EW 3.

I'NVENTOR OSEPH F. C

BY WM ATTORNEY.

3,516,464 APPARATUS AND METHOD FOR REMOVING WOOD DEFECTS Joseph F. Cyr,Lebanon, reg., assignor to U.S. Plywood- Champion Papers Inc., acorporation of New York Filed July 22, 1968, Ser. No. 746,683 Int. Cl.B27d 5/00 U.S. Cl. 144309 14 Claims ABSTRACT OF THE DISCLOSURE Anapparatus and method is provided for deknotting wood, particularly thinwood sections such as veneer, and includes a plurality of strikingelements, such as rods positioned above the wood and means forperiodically forcing the rods into contact with the wood to therebyloosen and dislodge wood defects. Each rod is separately regulated tostrike the wood at predetermined intervals and each is provided withmeans to reciprocally move the rods in a plane substantially at rightangles to the wood which is being processed.

FIELD OF THE INVENTION This invention relates to apparatus and methodfor removing defects from any plane surface and particularly forremoving knots and other similar defects from wood. More particularlythe invention relates to an apparatus and a method for removing knotsfrom thin wood sections such as wood veneers without adversely affectingthe strength or structure of the surrounding wood.

An apparatus and method is provided for deknotting wood, particularlythin wood sections such as veneer, and includes a plurality of strikingelements, such as rods positioned above the wood and means forperiodically forcing the rods into contact with the wood to therebyloosen and dislodge wood defects. Each rod is separately regulated tostrike the wood at predetermined intervals and each is provided withmeans to reciprocally move the rods in a plane substantially at rightangles to the wood which is being processed.

A common and continuing problem encountered during the manufacture ofunsurfaced and overlaid plywood, veneer, and other similar productsfabricated from thin sections of wood is the presence of defects such asknots, incipient decay, rot, pitch pockets, and the like which tend tofall out during the manufacturing process thereby impairing the qualityand spoiling the utility and appearance of the wood. These defects areoften characterized by being continuous between the plane surfaces ofthe thin sections of the wood and when the material from these defectsfalls from the wood it is frequently responsible for damage to equipmentas well as harmful to the wood itself. For example, the rubber rolls ofglue applicator machines can be damaged by hard pieces of knot.Furthermore, the glue in the applicator machines can be contaminated bythe knots, rots and other material. In addition, if this undesirablematerial is present, it can be pressed into and mar the surface of aplywood panel, or the overlaid face of a composite panel duringprocessing. Of ever greater importance, these materials can find theirway bet-ween plies in plywood to prevent proper bonding, thereby causingtotal loss or at least reducing the value of the panel.

Wood veneer and plywood are overlaid with a variety of differentmaterials, such as decorative wood veneegs, paper, cloth, etc. toproduce desired products. Open de fects in the wood have to be filledwith a type of wood putty so that they may present a better surface forgluing both in ordinary plywood and particularly in overlaid UnitedStates Patent 0 ice wood. Open, loose, and even solid knots present aparticularly poor surface for glue bonding and it is also prior toprocessing the wood so that the best surface for bonding may be achievedby filling the vacant space with a better material.

In view of the importance to the industry of a process which willeffectively remove all loose knots from the veneer early in theprocessing thereof, there is a continuous effort to develop such aprocess. A wide variety of .devices and processes have been employed butfew have been successful. One such process requires the precise cuttingof the knots or other defects from the Wood and then applying round orboat shaped patches to the' vacated area of the wood. Such a process isexpensive and slow and is accompanied by serious waste of valuablepatching material and the large cut of wood is taken from around theknot.

It is obvious, therefore, that there is still a need for an apparatusand process which can effectively and economically dislodge knots andother wood defects for the subsequent filling of the hole by a suitablewood filler composition to a plane surface, and for final overlayingwith expensive surfacing veneers or abrasive resistant resin impregnatedpapers.

DESCRIPTION OF THE INVENTION Broadly, the present invention is directedto an apparatus for deknotting wood comprising a support member forsupporting the wood, a plurality of striking elements, for example, rodspositioned above the wood, and means to move the rods such that they arecaused to strike the upper surface of the wood to thereby loosen anddislodge the knots and other defects. Rods are used to denote all typesof striking elements. In the preferred embodiment, each rod isindependently reciprocated and periodically strikes the wood. The rods,which are generally raised and lowered in a plane substantially at rightangles to the wood passing beneath them, are arranged such that theyextend, at spaced intervals, across substantially the entire width ofthe wood. With this arrangement, all of the knots in the veneer aresubjected to the force of the striking rods.

Since the rods can be individually controlled, they may be timed tostrike the wood with varying frequencies and at various intervals, thatis other than simultaneously. Several rows of aligned rods may bepositioned together, and with individual rod timing, the force appliedto the veneer is such as to cause it to vibrate and release virtuallyall releasable knots and defects. This effect is accomplished withoutdamage to the veneer due to the strike' of the rod since a large forceis not required.

A further important feature of the invention is the means employed toraise and lower the rods in a reciprocal manner. In the most desiredembodiment, several spring coils are positioned about each rod and areseparated by a flanged member which is secured to the rod. When a forceis applied to the flanged member to raise or lower the rod, the upper orlower coil is placed in compression and upon release of the pressure,the coils serve to cause the rod to oscillate slightly, therebypermitting the rod to strike the wood several times in quick succession.The result is that the wood is subject to the several rod forces in thesame area, thus further increasing the effective deknotting force of theapparatus.

DESCRIPTION OF THE DRAWINGS The invention will be more readilyunderstood by referring to the drawings, wherein FIG. 1 is an isometricview of the apparatus of the invention; and

FIGS. 2, 3 and 4 are enlarged views of a rod employed in the apparatusof FIG. 1, in various positions during a single cycle; and

FIG. is a side view in cross section of the rod assembly illustrated inFIG. 2.

Referring to the drawings, in FIG. 1 there is shown a deknottingapparatus designated generally by the numeral including a base supportmember 12 which supports the wood to be deknotted such as veneer strip14. As shown, the veneer is marked by a number of knots and otherdefects which are indicated by the numeral 15. A plurality of rods 16,positioned above the support member 12, are held in a substantiallyvertical position by frame means 18 comprising an upper segment 20 and alower segment 22. The segments are each provided with a plurality ofopenings such as at 24, 26 through which the rods 16 project and whichaid in the alignment of the rods. The frame is fixed above the supportmember by means of bars 28, 30 which are secured at their base to thesupport member 12. The rods are surrounded by spring means 32 and eachrod is equipped with a flanged segment 34 which is secured to the rodsuch as by welding. In each rod assembly, the flanged segment is indirect contact with the spring means. A shaft 36, which is caused torotate by motor means 38, is positioned above the support member 12 andadjacent the rods 16. A plurality of cams are firmly attached to andspaced along the shaft 36, and are positioned such that one cam isproximate each flanged segment 34. The cams are spirally mounted alongthe shaft 36, that is, the projecting portion 42 of each cam 40 isdisplaced slightly about the shaft relative to the position of theprojecting portion of the adjacent cam. In this manner, the variousflanged segments 34 are contacted by the cams at diffeernt times duringthe revolution of the shaft 36. .A receptacle 44 for receiving thedislodged knots is placed in the support member 12 directly beneath therods.

In the operation of the apparatus, the veneer strip 14 is passed alongthe surface of the support member 12 by means (not shown) such as aconveyor belt or the like. The rods 16 are normally positioned slightlyabove the surface of the veneer strip 14. However, as the shaft 36 isrotated, cams 40 apply a force to the flanged segments 34 through theprojecting portions 42. Each cam trips the associated rod as it isrotated into contact with the flanged segment on the rod and because ofthe spiral arrangement of the cams, each rod is moved at a timedifferent than the rod adjacent to it. Of course, the cam positions maybe arranged in virtually any configuration along the shaft to obtain themost suitable timing for a given system. As the flanged segment isforced upward by the cam, the rod is lifted a short distance andpressure is applied to the coil spring 32. Upon further rotation of theshaft, the cam force is released from the flanged segment and the uppercoil spring pressure urges the rod downward causing it to strike thepassing veneer strip. A damping as well as an oscillating effect isachieved by the presence of lower spring coil 46 (shown in FIG. 2) whichis positioned about the rod below the flanged segment. This action isrepeated for each rod at least once for each revolution of the shaft andthe resultant effect is to vibrate the veneer strip as it passes,thereby dislodging the various wood defects which are then collected inthe receptacle 44.

The operation of the rods is more clearly illustrated in FIGS. 2, 3 and4. In FIG. 2, the projecting portion 42 of the cam 40 is shown liftingthe flanged segment 34 and thus the rod 16 as the shaft 36 rotates. Thecoil spring 32 is placed in compression by the force of the flangedsegment as it is lifted. FIG. 3 shows the rod assembly immediately afterthe cam is rotated out of contact with the flanged segment. The rod 16is in a position ot strike the veneer, that is, at the lowest point inits path of travel due to the pressure released by coil spring 32.However, the FIG. 4 illustrates the same rod assembly as the shaft 36continues to rotate. The rod 16 is now forced upward by lower coilspring 46 after striking the veneer. The

oscillating motion of the rod continues for a brief period untildampened by the coil spring friction. During the oscillation period, therod strikes the veneer several times as hereinbefore explained.

FIG. 5 illustrates the rod assembly in cross section. As theer shown,the upper coil spring 32 is positioned between flanged segment 34 andframe member 20 and is connected to both while lower spring coil 46 isconnected to flanged segment 34 and frame member 36. Openings 24, 26align rod 16 and aid in maintaining the direction of movement of therod. The upper spring coil 32 is preferably somewhat stronger than thelower coil 46 in order that the above-described oscillating motion ofthe rod can be more readily effected.

The rods can be constructed of any sturdy material which will Withstandthe frequent striking of the Wood. Steel rods approximately 8 incheslong and inch in diameter have been employed quite successfully forprolonged operating periods without requiring replacement. The cyclefrequency of the rods is a function of several variables such as springtension, size of cam projecting portion which would also control thelength of rod movement, rate of veneer travel and speed of shaftrotation. By way of example, a shaft speed of 700 revolutions per minutefor a one inch. diameter shaft with cam and rod assemblies spaced oneinch apart, together with a veneer speed of 50 feet per minute haveresulted in a desirable cycle frequency. Obviously, variations of theseparameters is well within the mechanical skill of an operator.

Many modifications of the apparatus of the invention are readilyapparent and are intended to be within the purview of this invention.For example, while the abovedescribed cam-shaft arrangement is believedto be a simple, inexpensive and effective means for imparting thedesired motion to the rods, mechanical equivalents such as overheaddrive devices can also be employed. In addition, the rods may bedispersed over a greater area of the veneer to provide a greateroperating force. Several rows of rods, staggered laterally, would ensurethat various portions of knots to be removed would be struck by therods. The rods can also assume various shapes, particularly at the endwhich strikes the veneer. This lower end can be equipped with shoes tosoften the blow to the wood, if desired, although this expedient has notbeen found to be necessary. An enlarged lower rod portion designed tostrike a greater area of passing veneer is also a feature which isreadily incorporated into the apparatus.

The term rod as used herein and in the appended claims is intended toinclude within its meaning any instrument which will impart thenecessary force to the Wood to loosen and dislodge the wood defectstherein in the manner described.

From the foregoing, it will be appreciated that the apparatus andprocess of the invention provide a simple, economical and eflicientsolution to the long standing problem of removing defects from wood. Theapparatus has been successively employed in removing defects from woodof various thicknesses quickly and without injury to the surroundingwood.

The embodiments of the invention in which an exclusive property orprivilege is claimed are as follows:

1. An apparatus for removing defects from wood comprising (a) a basesupport member for supporting the wood;

(b) a plurality of rods positioned above the wood on said supportmember; and

(0) means for reciprocating said rods to periodically contact said wood,thereby causing said wood to be continuously subjected to the force ofsaid moving rods whereby the defects in said wood are loosened anddislodged.

2. The apparatus of claim 1 wherein said rods are positionedsubstantially at a right angle to said wood.

3. The apparatus of claim 1 wherein said rods are arranged such thatthey extend at spaced intervals across substantially the entire width ofsaid wood and are aligned in at least one row.

4. The apparatus of claim 3 wherein means for regulating the movement ofeach rod independently of any other rod are included.

5. The apparatus of claim 1 wherein means for receiving the dislodgeddefects are provided below said wood and directly below said rods.

6. An apparatus for removing defects from wood comprising (a) a basesupport member for supporting the wood;

(b) a plurality of rods positioned above and substantially at rightangles to the wood on said support member;

(c) spring means aflixed to each of said rods;

((1) means for periodically applying a force to said spring meanssubstantially along the longitudinal axis of said rods whereby said rodsare alternately raised and lowered, said force being sufficient to causesaid rods to contact said wood when lowered to thereby loosen anddislodge the defects in the wood.

7. The apparatus of claim 6 wherein means for regulating the movement ofeach rod independently of any other rod is provided.

8. The apparatus of claim 6 wherein said spring means on each rod isdivided into an upper spring coil and a lower spring coil, a flangedsegment is secured to each rod and positioned between said upper andlower spring coils, and said force is applied to said flanged segment.

9. An apparatus for removing defects from wood, comprising (a) a basesupport member for supporting the wood;

(b) frame means secured to said base support member, said frame meanshaving spaced substantially parallel upper and lower segments positionedabove said support member, each of said segments having a plurality ofopenings therein;

(c) a plurality of rods secured to said frame means,

said rods extending through said openings, and positioned above andsubstantially at right angles to the wood to be processed;

(d) a flanged segment secured to each rod;

(e) spring means affixed to each rod, said spring means being positionedbetween said flanged segment and 45 said frame segments; (f) a rotatableshaft secured to said base support member and positioned adjacent tosaid rods;

(g) a plurality of cams aflixed to said shaft and placed thereon suchthat upon rotation of said shaft, said cams contact said flangedsegments on Said rods; and

(h) means to rotate said shaft whereby said flanged segments arecontacted by said cams to reciprocate said rods intocontact with thewood to thereby loosen and dislodge the defects therein.

10. The apparatus of claim 9 wherein said cams are spirally mountedabout the axis of said shaft such that said rods are reciprocated atdifferent periods during the revolution of the shaft.

11. The apparatus of claim 9 wherein said spring means is divided intoan upper spring coil and a lower spring coil, each coil being incommunication with said flanged segment.

12. The apparatus of claim 9 wherein said rods are arranged such thatthey extend across substantially the entire width of the wood to beprocessed and are aligned in at least one row.

13. A method for removing wood defects from wood, comprising passingsaid wood over a supporting surface;

applying a plurality of forces to the upper surface of said wood, saidforces being applied at substantially right angles to said upper surfaceand at spaced intervals across substantially the entire width of saidWood;

regulating the application of said forces such that each force iscyclically applied and less than all of said forces are simultaneouslyapplied whereby said wood is caused to vibrate to thereby loosen anddislodge the defects therein.

14. The method of claim 13 wherein the step of oscillating said forcesduring the application thereof is added.

References Cited UNITED STATES PATENTS GERALD A. DOST, Primary ExaminerU.S. c1. X.R.

